The disclosed embodiments of the present invention relate to a dynamic comparator, and more particularly, to an apparatus and method for performing offset adjustment upon a dynamic comparator.
In today's world where demand for portable devices powered by battery devices is increasing, a major thrust is given towards low power methodologies for high resolution and high speed applications. This reduction in power can be achieved by moving towards smaller feature size processes. However, when smaller feature size processes are adopted, the process variations and other non-idealities will greatly affect the overall performance of the devices. One such application where low power, high resolution and high speed are required is an analog-to-digital converter (ADC) for a portable device. In the past, pre-amplifier based comparators have been used for ADC architecture such as a flash ADC. The main drawback of pre-amplifier based comparators is the high constant power consumption. To overcome this problem, dynamic comparators are used. Dynamic comparators consume power only when making signal comparison. There is no static current, thus requiring much less power as compared to the pre-amplifier based comparators.
Compared to the flash ADC using pre-amplifier based comparators, a fully dynamic flash ADC is realized without track/hold circuits, resistor strings and pre-amplifiers, and the only analog signal is the input signal to be converted into a digital output, where each dynamic comparator senses the input signal around the clock edge and compares the input signal with its built-in offset which is equivalent to a reference voltage used by a pre-amplifier based comparator.
In general, a bias condition of the dynamic comparator would affect the comparator offset possessed by the dynamic comparator. The bias condition of the dynamic comparator may vary due to certain factors. For example, the comparator offset is very sensitive to supply voltage variation, temperature variation, etc. Consequently, the comparator offset becomes a major concern in practical applications.